In recent years, methods for manufacturing imaging devices using ink-jet apparatuses have been attracting attention. FIGS. 8(A) and 8(B) are plan views of a typical ink-jet apparatus.
As shown in FIGS. 8(A) and 8(B), the ink-jet apparatus includes a pedestal 41, a substrate transport stage 42, a gate-like gantry 43, and a line scan head 50.
As shown in FIGS. 8(A) and 8(B), the substrate transport stage 42 relatively moves. Ink is properly discharged from the line scan head 50 during the movement and is applied to a coating area 44 of a substrate 10 placed on the substrate transport stage 42, printing the substrate 10.
FIG. 9 is a schematic diagram of the line scan head 50. As shown in FIG. 9, the line scan head 50 includes a plurality of ink-jet heads 51 and a casing 52 that holds the ink-jet heads 51. The ink-jet heads 51 are arranged in a direction orthogonal to the print-scan direction of a substrate, the ink-jet heads 51 being so wide as to print the substrate in one printing/scanning operation. The line scan head 50 includes ink supply pipes 53 that supply ink for printing from the outside.
A feature of an ink-jet apparatus is to inexpensively manufacture devices with a simple manufacturing process. In an ink-jet apparatus provided with the line scan head having the arranged ink-jet heads 51, however, the positions of the ink-jet heads 51 are hard to stabilize, making it difficult to form fine-pitch patterns on a substrate.
In order to overcome this drawback, the line scan head 50 is devised to actively correct the displacements of the ink-jet heads 51 (Japanese Patent Laid-Open No. 2002-228822).
FIGS. 10(A) and 10(B) are schematic diagrams showing the configuration of the conventional line scan head 50 described in Japanese Patent Laid-Open No. 2002-228822. FIG. 10(A) is a side view and FIG. 10(B) is a perspective view.
Ink-jet heads 301, 302, and 303 are fixed to a reference base 321 and stages 322 and 323 via ink-jet head fixing members 311, 312, and 313 shown in FIG. 10(B). The stages 322 and 323 are fixed to the reference base 321 via piezoelectric elements 341 and 342 acting as actuators.
When the ink-jet heads 301 and 303 are displaced relative to the ink-jet head 302, the piezoelectric elements 341 and 342 are driven by a desired displacement so as to be corrected to design locations.
In the conventional configuration, however, the piezoelectric elements acting as actuators need to be operated to fix the positions of the ink-jet heads. Thus, the ink-jet heads cannot be disposed close to each other with a high density, making it difficult to dispose the ink-jet heads.
If the ink-jet heads are disposed in the conventional configuration, the ink-jet heads are sequentially disposed through a predetermined actuator mechanism, increasing spacing between the ink-jet heads. Thus, the line scan head and the ink-jet apparatus including the line scan head increase in size.
This may cause a time difference before the application of ink depending on the installation positions of the ink-jet heads, in substrate scanning for printing. The time difference leads to uneven drying, considerably deteriorating printing quality.
Moreover, the actuators need to be always driven in order to keep the positions of the ink-jet heads disposed on the line scan head, disadvantageously causing higher power consumption and heat generation.
The line scan head containing a heat source, in particular, may reduce the accuracy of component assembly. Furthermore, once power is shut down for maintenance of apparatuses, the kept positions of the ink-jet heads are reset, disadvantageously reducing positional repeatability.
An object of the present invention is to provide an ink-jet apparatus including a small line scan head with densely mounted ink-jet heads, which guarantees the positions of the ink-jet heads for a long period to solve the conventional problems.